The force last month admitted it let down the 1,400 victims of child sex abuse in Rotherham between 1997 and 2013 highlighted in Alexis Jay’s inquiry.

Today’s HMIC report into child protection in general across South Yorkshire praised ‘good practice’ in tackling the problem in Rotherham and Sheffield, but said police needed to do better in Doncaster and Barnsley. It raised “significant concerns” about how well police understood the needs of children in care homes, particularly in Doncaster.

In one disturbing case, it took a month for three young girls in a children’s care home who were “involved in increasingly risky behaviour” to be separated despite them frequently going missing and being sexually assaulted by several men.

Interim plans “did not sufficiently protect the girls” and officers who knew they were still at risk of abuse did not tell their bosses of their concerns.

There was also insufficient action taken against the men who were exploiting the girls, such as investigating their behaviour, monitoring their activities or identifying other children who might be in contact with them, the report said.

However, the report praised the force for undertaking “prompt and thorough” inquiries in most cases.According to the report: “When allegations of child sexual exploitation were made, the depth of investigations varied. In one case, in the face of parental indifference and a long history of the child going missing, the police searched for the girl, pursued the men they believed were abusing her and brought together agencies to plan for the future.

“In other cases, children under 16 went missing frequently – 30 or 40 times was not uncommon – with little police activity and no search for suspects or follow-up action.”

Former police commissioner Shaun Wright, who resigned in the aftermath of Professor Jay’s report, has invested £4.5 million in expanding child protection and public protection services.

In November a separate HMIC review said children were not being properly protected from sexual exploitation, though a follow-up this summer said improvements had been made.

Last month a separate HMIC report said officers in South Yorkshire Police’s public protection unit, which deals with rape and serious sexual assault, spend a “great deal of time” trying to “disprove” the word of victims.

HM Inspector of Constabulary Dru Sharpling said today: “South Yorkshire Police is clearly prioritising child protection, and has made some good progress, particularly in cases where concerns about children have been clearly identified at the outset.

“We are concerned that force practice is inconsistent so not all children receive the standard of treatment they deserve. More must be done to improve the care of children in custody.

“We were also concerned about the lack of understanding of the risk posed by offenders who target vulnerable children, and shortcomings in the protection of children in care.

“We encourage South Yorkshire Police to address our concerns as a matter of urgency, and have asked that within six weeks it provides us with a plan on how it intends to act on our recommendations.”

HMIC said most police staff were well trained and committed to their roles. It added: “For the most part, the force responded well when the case clearly identified a child in need of protection, but in difficult or complex cases the response was weak.”

The report said that because of the way information was held and archived, “officers do not always have access to all the information they need to make good decisions”.

In response, Assistant Chief Constable Ingrid Lee said: “South Yorkshire Police has made, and continues to make, great strides in child protection and this report makes recommendations which allow us to progress further.

“I’m pleased to see that the report recognises the sensitive way in which we approach victims, as this is absolutely crucial if we are to assist those in fear today of coming forward tomorrow. We take child protection issues extremely seriously and will work with all of our partners to ensure every aspect of the child’s safety is considered in all of our decisions.”

She added: “To improve consistency across the force we have developed a Central Referral Unit where all referrals relating to children are received from police and partner agencies; this ensures a structured and multi-agency approach to all child safeguarding investigations and concerns.

“We’ve also set up co-located multi agency teams in every district. These teams comprise specialist officers from public protection, social workers and representatives from Barnardo’s. In Doncaster, we are also piloting the role of a Children in Care Liaison Officer.

“This is a liaison officer who engages with the children and staff of care homes by providing a positive role model, a link into the specialist services and a support to reduce the criminalisation and harm of children in care.

“We’re also working creatively to prevent harm. We now use polygraph tests with known sex offenders including those who have had indecent images of children to assess the risk they pose.

“We also share information with the public. Under the domestic abuse disclosure scheme - also known as ‘Clare’s Law’ - anyone who is concerned about the risk of domestic abuse can be provided with information about a person’s relevant previous convictions, intelligence and concerning behaviour. We’ve made 18 disclosures since the scheme was introduced in March 2014.

“And similarly under the child sex offender disclosure scheme, or ‘Sarah’s Law’ as it’s more commonly known, convictions can be disclosed for child sex offences and other convictions, intelligence or concerning behaviour which is relevant to the safeguarding of children.

“We’ve made ten disclosures in the last nine months, we will never be able to identify the true benefit of this disclosure or how many children this has saved from harm.”

“We understand the complexities of child sexual exploitation and we don’t shy away from difficult investigations. All victims receive the highest standards of service possible.

“If we find evidence that appropriate action has not been taken we will ensure that is dealt with properly and robustly.”

The report comes weeks after the publication of the Alexis Jay report, which described how council and police officials turned a blind eyes as Asian gangs abused hundreds of vulnerable young people over 14 years.

Christine Empson, Divisional Manager for Victim Support in South Yorkshire, said: “Children in Rotherham who were being sexually exploited were badly let down for a long time. Improvements have been made, to the extent that police in Rotherham were not singled out in this inspection.

“But clearly more needs to be done across the county - and the country - to make sure the same mistakes are never repeated. What victims want most is to know that other people will not suffer at the hands of the same criminal.

“We will continue to work with South Yorkshire Police to make sure crime victims get the support they need and the respect they deserve.”

Canon Dr Alan Billings, Labour’s candidate to replace Shaun Wright in the South Yorkshire Police and Crime Commissioner election, said: “This report from HMIC shows that South Yorkshire Police are still failing in too many instances to protect vulnerable children adequately or pursue the criminals carrying out such appalling crimes.

“If elected as Police and Crime Commissioner, turning this round will be a top priority. That means implementing the recommendations of this report in full, vastly improving understanding of these crimes and how to deal with young people at risk, and providing proper support to victims.

“As someone with no prior involvement with South Yorkshire Police, but with experience of the criminal justice system in relation to young people, I can ensure that the Chief Constable is held to account in putting right these failures to protect the victims and bring the perpetrators to justice.”